Dental flask



S. A. LEADER 'DENTAL FLASK May 13; 1947;

Filed Dec. 29, 1944 2 Sheets-Sheet 1 INVENTOR SIDNEY ARTHUR LEA DIER hATTORNEYS May 13, 1947. s. A. LEADER DENTAL FLASK Filed D60. 29, 1944 2Sheets-Sheet 2 INVENTOR 'ISIDNEYARTHUR. LEADER y #1, ATTORNEYS PatentedMay 13, 1947 DENTAL FLASK Sidney Arthur Leader, London, England,assignor to Portland Plastics Limited, London, England,

a British company Application December 29, 1944, Serial No. 570,230 InGreat Britain January 28, 1944 Claims.

This invention relates to dental flasks.

As is well known many materials used for making dentures and inparticular acrylic resins such as those made from a mixture of monomericand polymerised methyl methacrylate contract during the curing processwhereby defects are liable to arise in the finished denture.

Attempts have been made to overcome this disadvantage by tightening thenuts employed in some types of dental flask from time to time during thecuring or by the use of clamps such as that described in my UnitedKingdom specification No. 553,079.

It is an object of the present invention to provide a dental flaskhaving means integral therewith for exerting pressure on the denturematerial during curing.

It is a further object of the invention to provide in such a flask meansfor facilitating the removal of the plaster moulds from the flask aftercuring.

Accordingly, the present invention provides a dental flask comp-risingan upper and a lower portion, a plurality of spring-loaded alignmentposts each slidably disposed in a chamber in either the upper or lowerportion of the flask a portion of each of said posts projecting througha hole in the chamber, which is otherwise closed, said projectingportion of each of the posts passing through a hole in the other part ofthe flask and means for compressing the springs so that the portions ofthe flask are urged together.

According to a preferred embodiment the present invention provides adental flask comprising an upper and a lower portion, a plurality ofspring-loaded alignment posts each slidably disposed in a chamber ineither the upper or lower portion of the flask, a portion of each ofsaid posts projecting through a hole in the chamber, which is otherwiseclosed, said projecting portion of each of the posts being provided witha screw thread and passing through a hole in the other part of the flaskand co-operating with a nut.

Instead of the alignment posts being provided with screw threads andnuts, they may be provided with slots into which wedges are driven tocompress the springs.

In use the flask is slightly overfilled with the material from which thedenture is to be made and. the nuts tightened or the wedges driven in.As the material contracts during the curing process the two parts of theflask are constantly urged together by the action of the springs.

Brfiierably one of the posts is disposed at the 2. back of the flask andis provided with a spring more powerful than the others to ensure thatthe back teeth of the denture are not higher than the front.

Preferably also the upper and lower walls of the flask are provided withdetachable portions asymmetrically disposed so that on tapping theseportions after the curing has been completed, the plastic moulds areremoved more easily since leverage is exerted thereon.

The chambers are conveniently closed by means of screwed plugs and thebottoms of the posts are conveniently provided either with transverselyprojecting members co-operating with slots in the walls of the chambersto lock the posts against rotational movement, Or a part of each postinside the chamber is provided with a flat which co-operates with a setscrew passing through the wall of the chamber to lock the post againstrotational movement.

Preferably alsothe nuts if used are. provided with non-threaded portionsat the bottoms thereof to facilitate engagement of the nuts with thescrew threads of the posts and to allow the bottoms of the nuts to bescrewed down below the ends of the screw threads of the posts.

The invention will now be further described byway of example withreference to the accompanying drawings, in which:

Fig. 1 is a perspective view of the. flask with the upper and lowerportions separated and one alignment post removed;

Fig. 2 is a view of one of the alignment posts with its associatedspring and nut;

Fig. 3 is a top plan view of the flask;

Fig. 4 is a section on the line A.A of Fig. 3;

Fig, 5 is a sectional view of one of the nuts;

Fig. 6 shows a modified alignment post with its associated spring andwedgaand Fig. 7 is a fragmentary view showing a modified device forlocking the posts against rotational movement and also a preferred formof nut.

Referring to Figs. 1 to 5 of the drawings, the flask has a lower part Iand an upper part 2. Three alignment posts 3 are disposed in chambers 4.Each alignment post is threaded at its upper end to receive a nut 5 andis surrounded by a spring 6. The bottom of each alignment post isprovided with a transversely projecting member 1 co-operating with slots8 in the wall of the chamber to prevent rotational movement of thealignment post. The bottom of each chamber is closed by a screwed plug 9having two blind holes Ill for the reception of a key to screw andunscrew the plug. The upper and lower parts are each provided with aremovable member H (which is removed in Fig. 1 but present in Figs. 3and 4). The alignment posts project through holes l2 in the upper partwhich is provided with recesses as shown to receive the nuts which havetheir lower parts 13 free from screw threads as shown in Fig. 5 for thepurpose referred to above.

Parts are removed from the lower and pper portions l and 2 to providerecesses l4 into which levers can be inserted after the curing operationto facilitate the separation of the portions I and 2. One of therecesses I4 is also sufliciently large to receive a ring l5 as shownwhich facilitates the removal of the flask from the hot liquid orchamber, e. g. oven, in which the curing normally takes place.

Referring now to Fig. 6 of the drawings, the alignment post, spring andnut of Fig. 2 is replaced by the alignment post I6 having projectingmembers I! (similar to the members I in Fig. 2). I'he spring 3 issimilar to the spring 6 in Fig. 2. The alignment post has a slot 9 toreceive the wedge 28.

The flask according to the present invention has the advantage that theclamping means is integral with the flask, the spring is enclosed andthus protected from contamination by the plaster. If desired a greaterpressure can be exerted on the back of the flask by the use of a morepowerful spring in the back chamber.

Furthermore the plaster can be easily removed by tapping the members IIand the flask is of robust construction.

Referring now to Fig. 7 of the drawings, this shows a modification ofthe flask shown in Fig. 4, in which instead of the post 3 being lockedagainst rotational movement by the projecting member I co-operating withthe slots 8 the locking is effected by the set screw 22 bearing againstthe flat 2| on the post 3. This modification also shows a preferred formof nut 23 having a tommy bar 24 which avoids the use of a spanner. Italso shows in place of the blind holes ill a cut 25 into which a screwdriver can be inserted for removing the screwed plug 9. The bolt 3 istapered to the thread thereof, which frees the upper part 2, which isvery desirable in dental practice when the upper part cannot descendvertically owing to undercuts in the denture but nevertheless the upperpart 2 registers accurately when the bolt 3 rises on tightening the nut.Preferably the chambers 4 contain graphite or other lubricant.

I claim:

1. A dental flask comprising an upper and a lower portion, a pluralityof chambers each having one closed end and an opening at the other endin one of said portions, a post slidably disposed in each of saidchambers and having a portion projecting through said opening in saidchamber, a spring in each chamber normally urging the post thereintoward the closed end of said chamber, said projecting portion of eachof said posts registering with a hole in the other portion of the flaskand means cooperating with said other portion of said flask and saidpost for compressing the springs so that the two portions of the flaskare urged together.

2. A dental flask comprising an upper and a lower portion, a pluralityof chambers each having one closed end and an opening in the other endin one of said portions, a post slidably disposed in each of saidchambers and having a 4 screw threaded portion projecting through saidopening in said chamber, a spring in each chamber normally urging thepost therein toward the closed end of said chamber, said screw threadedprojecting portion of each of said posts registering with a hole in theother portion of the flask and a nut co-operating with each of saidscrew threaded projecting portions and said other portion of said flaskto urge the two portions of the flask together.

3. A dental flask comprising an upper and a lower portion, a pluralityof chambers each having one closed end and an opening at the other endin one of said portions, a post slidably disposed in each of saidchambers and having a slotted portion projecting through said opening insaid chamber, a spring in each chamber normally urging the post thereintoward the closed end of said chamber, said slotted projecting portionof each of said posts registering with a hole in the other portion ofthe flask and a wedge co-operating with each of said slotted projectionsand with said other portion of said flask to urge the two portions ofthe flask together.

4. A dental flask comprising an upper and a lower portion, a pluralityof chambers each having one closed end and an opening at the other endin one of said portions, a post slidably disposed in each of saidchambers and having a portion projecting through said opening in saidchamber, a spring in each chamber normally urging the post thereintoward said closed end said projecting portion of each of said postsregistering with a hole in the other portion of the flask and meanscooperating with said post and said other portion of said flask forcompressing the springs so that the two portions of the flask are urgedtogether, one of said posts having a spring more powerful than those ofthe other posts.

5. A dental flask comprising an upper and a lower portion, each of saidportions having a detachable asymmetrically disposed plate forming partof a horizontal surface thereof, a plurality of chambers each having oneclosed end and an opening at the other end in one of said portions, apost slidably disposed in each of said chambers and having a portionprojecting through a hole in said chamber, a spring in each chambernormally urging the post therein toward the closed end of said chamber,said projecting portion of each of said posts registering with a hole inthe other portion of the flask and means cooperating with said posts andsaid other portion of said flask for compressing the springs so that thetwo portions of the flask are urged together.

6. A dental flask comprising an upper and a lower portion, a pluralityof chambers having open opposite ends in one of said portions, a plugthreaded into one end of each of said chambers, a post slidably disposedin each of said chambers and having a portion projecting through theother open end of said chamber, a

spring in each of said chambers normally urgin the post therein towardsaid plug, said projecting portion of each of said posts registeringwith a hole in the other portion of the flask and means cooperating withsaid posts and said other portion of said flask for compressing thesprings so that the two portions of the flask are urged together.

7. A dental flask comprisin an upper and a lower portion, a plurality oflongitudinally slotted chambers each having one closed end and anopening at the other end in one of said portions, a post one slidablydisposed in each of said chambers and having a transversely projectingmember cooperating with said longitudinal slot and also a portionprojecting through said opening in said chamber, a spring in eachchamber normally urging the posts therein toward said closed end saidprojecting portion of each of said posts registering with a hole in theother portion of the flask and means cooperating with said posts andsaid other portion of the flask for compressing the springs so that thetwo portions of the flask are urged together.

8. A dental flask comprising an upper and a lower portion, a pluralityof chambers each having one closed end and an opening at the other endin one of said portions, a cylindrical post slidably disposed in each ofsaid chambers and having a portion projecting through said opening insaid chamber and a flat on a portion of the post inside the chamber, aspring in each chamber normally urging the post therein toward saidclosed end, a set screw passing through the wall of the chamber andadapted to bear against the flat to prevent rotational movement of saidpost, said projecting portion of each of said posts registering with ahole in the other portion of the flask and means cooperating with saidposts and said other portion of said flask for compressing the springsso that the two portions of the flask are urged together.

9. A dental flask comprising an upper and a lower portion, a pluralityof chambers each having one closed end and an opening at the oppositeend in one of said portions, a post slidably disposed in each of saidchambers and having a portion projecting through said opening in saidchamber, said projecting portion of each of said posts registering witha hole in the other portion of the flask, a sprin in each chamber anddisposed around each of said posts normally urging said post toward saidclosed end of said chamber and means cooperating with said posts andsaid other portion of said flask for compressing the springs so that thetwo portions of the flask are urged together. I

10. A dental flask comprising an upper and a lower portion, threechambers having opposite open ends in the lower portion, a cylindricalpost slidably disposed in each of Said chambers and having a screwthreaded portion projecting through an open end of said chamber and alsoa flat on a portion of the post inside the chamber, a plug closing theopposite open end of each of said chambers, a. coil spring around eachof said posts normally urging said post toward said plugs the springaround one of the posts being more powerful than the others, a set screwone passing through the wall of each chamber and adapted to bear againstthe flat of said posts therein to prevent rotational movement, saidprojecting portion of each of said posts registering with a hole in thetop portion of the flask, and a nut provided with a non-threaded portionat the bottom thereof co-operating with each of said screw threadedportions and said top portion of said flask to urge the top and lowerportions of the flask together.

SIDNEY ARTHUR LEADER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,537,884 Romine et a1 May 12,1925 1,613,506 Delohi Jan. 4, 1927 1,922,875 Birdlebough Aug. 15, 19332,102,266 Handler Dec. 14, 1937 2,243,950 Franwick June 3, 19412,333,833 Tryfus Nov. 9, 1943 2,359,152 Pryor et a1 Sept. 26, 1944Certificate of Correction Patent No. 2,420,545. May 13, 1947. SIDNEYARTHUR LEADER It is hereby certified that errors appear in the printedspecification of the above numbered patent requiring correction asfollows: Column 5, line 2, claim 7, after post strike out one; column 6,line 16, claim 10, after screw strike out one; and that the said LettersPatent should be read with these corrections therein that the same mayconform to the record of the case in the Patent Office.

Signed and sealed this 29th day of July, A. D. 1947.

LESLIE FRAZER,

First Assistant Uommz'ssioner of Patents.

